diff --git a/config/test.exs b/config/test.exs
index 0b7508e..6673e1f 100644
--- a/config/test.exs
+++ b/config/test.exs
@@ -3,7 +3,6 @@ use Mix.Config
 config :dataloader, Dataloader.TestRepo,
   hostname: "localhost",
   database: "dataloader_test",
-  adapter: Ecto.Adapters.Postgres,
   pool: Ecto.Adapters.SQL.Sandbox
 
 config :dataloader, ecto_repos: [Dataloader.TestRepo]
diff --git a/mix.exs b/mix.exs
index eb2dc2f..51aae3e 100644
--- a/mix.exs
+++ b/mix.exs
@@ -47,8 +47,13 @@ defmodule Dataloader.Mixfile do
     ]
   end
 
+  # TODO: After Elixir 1.8, optional dependencies will be automatically
+  # included in `extra_applications`. So, it will be safe to remove this
+  # section.
+  #
+  # See: https://github.com/elixir-lang/elixir/pull/8263
   defp test_apps(:test) do
-    [:ecto, :postgrex]
+    [:ecto_sql, :postgrex]
   end
 
   defp test_apps(_), do: []
@@ -56,8 +61,8 @@ defmodule Dataloader.Mixfile do
   # Run "mix help deps" to learn about dependencies.
   defp deps do
     [
-      {:ecto, ">= 0.0.0", optional: true},
-      {:postgrex, ">= 0.0.0", only: :test},
+      {:ecto_sql, "~> 3.0", optional: true},
+      {:postgrex, "~> 0.14", only: :test},
       {:dialyxir, "~> 0.5", only: :dev},
       {:ex_doc, ">= 0.0.0", only: [:dev]}
       # {:dep_from_hexpm, "~> 0.3.0"},
diff --git a/mix.lock b/mix.lock
index a78bce8..3af6791 100644
--- a/mix.lock
+++ b/mix.lock
@@ -1,14 +1,16 @@
 %{
   "connection": {:hex, :connection, "1.0.4", "a1cae72211f0eef17705aaededacac3eb30e6625b04a6117c1b2db6ace7d5976", [:mix], [], "hexpm"},
-  "db_connection": {:hex, :db_connection, "1.1.3", "89b30ca1ef0a3b469b1c779579590688561d586694a3ce8792985d4d7e575a61", [:mix], [{:connection, "~> 1.0.2", [hex: :connection, repo: "hexpm", optional: false]}, {:poolboy, "~> 1.5", [hex: :poolboy, repo: "hexpm", optional: true]}, {:sbroker, "~> 1.0", [hex: :sbroker, repo: "hexpm", optional: true]}], "hexpm"},
-  "decimal": {:hex, :decimal, "1.5.0", "b0433a36d0e2430e3d50291b1c65f53c37d56f83665b43d79963684865beab68", [:mix], [], "hexpm"},
+  "db_connection": {:hex, :db_connection, "2.0.3", "b4e8aa43c100e16f122ccd6798cd51c48c79fd391c39d411f42b3cd765daccb0", [:mix], [{:connection, "~> 1.0.2", [hex: :connection, repo: "hexpm", optional: false]}], "hexpm"},
+  "decimal": {:hex, :decimal, "1.6.0", "bfd84d90ff966e1f5d4370bdd3943432d8f65f07d3bab48001aebd7030590dcc", [:mix], [], "hexpm"},
   "dialyxir": {:hex, :dialyxir, "0.5.1", "b331b091720fd93e878137add264bac4f644e1ddae07a70bf7062c7862c4b952", [:mix], [], "hexpm"},
   "earmark": {:hex, :earmark, "1.2.5", "4d21980d5d2862a2e13ec3c49ad9ad783ffc7ca5769cf6ff891a4553fbaae761", [:mix], [], "hexpm"},
-  "ecto": {:hex, :ecto, "2.2.10", "e7366dc82f48f8dd78fcbf3ab50985ceeb11cb3dc93435147c6e13f2cda0992e", [:mix], [{:db_connection, "~> 1.1", [hex: :db_connection, repo: "hexpm", optional: true]}, {:decimal, "~> 1.2", [hex: :decimal, repo: "hexpm", optional: false]}, {:mariaex, "~> 0.8.0", [hex: :mariaex, repo: "hexpm", optional: true]}, {:poison, "~> 2.2 or ~> 3.0", [hex: :poison, repo: "hexpm", optional: true]}, {:poolboy, "~> 1.5", [hex: :poolboy, repo: "hexpm", optional: false]}, {:postgrex, "~> 0.13.0", [hex: :postgrex, repo: "hexpm", optional: true]}, {:sbroker, "~> 1.0", [hex: :sbroker, repo: "hexpm", optional: true]}], "hexpm"},
+  "ecto": {:hex, :ecto, "3.0.5", "bf9329b56f781a67fdb19e92e6d9ed79c5c8b31d41653b79dafb7ceddfbe87e0", [:mix], [{:decimal, "~> 1.6", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:poison, "~> 2.2 or ~> 3.0", [hex: :poison, repo: "hexpm", optional: true]}], "hexpm"},
+  "ecto_sql": {:hex, :ecto_sql, "3.0.3", "dd17f2401a69bb2ec91d5564bd259ad0bc63ee32c2cb2e616d04f1559801dba6", [:mix], [{:db_connection, "~> 2.0", [hex: :db_connection, repo: "hexpm", optional: false]}, {:ecto, "~> 3.0.4", [hex: :ecto, repo: "hexpm", optional: false]}, {:mariaex, "~> 0.9.1", [hex: :mariaex, repo: "hexpm", optional: true]}, {:postgrex, "~> 0.14.0", [hex: :postgrex, repo: "hexpm", optional: true]}, {:telemetry, "~> 0.2.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm"},
   "ex_doc": {:hex, :ex_doc, "0.19.1", "519bb9c19526ca51d326c060cb1778d4a9056b190086a8c6c115828eaccea6cf", [:mix], [{:earmark, "~> 1.1", [hex: :earmark, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.7", [hex: :makeup_elixir, repo: "hexpm", optional: false]}], "hexpm"},
   "makeup": {:hex, :makeup, "0.5.1", "966c5c2296da272d42f1de178c1d135e432662eca795d6dc12e5e8787514edf7", [:mix], [{:nimble_parsec, "~> 0.2.2", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm"},
   "makeup_elixir": {:hex, :makeup_elixir, "0.8.0", "1204a2f5b4f181775a0e456154830524cf2207cf4f9112215c05e0b76e4eca8b", [:mix], [{:makeup, "~> 0.5.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 0.2.2", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm"},
   "nimble_parsec": {:hex, :nimble_parsec, "0.2.2", "d526b23bdceb04c7ad15b33c57c4526bf5f50aaa70c7c141b4b4624555c68259", [:mix], [], "hexpm"},
   "poolboy": {:hex, :poolboy, "1.5.1", "6b46163901cfd0a1b43d692657ed9d7e599853b3b21b95ae5ae0a777cf9b6ca8", [:rebar], [], "hexpm"},
-  "postgrex": {:hex, :postgrex, "0.13.5", "3d931aba29363e1443da167a4b12f06dcd171103c424de15e5f3fc2ba3e6d9c5", [:mix], [{:connection, "~> 1.0", [hex: :connection, repo: "hexpm", optional: false]}, {:db_connection, "~> 1.1", [hex: :db_connection, repo: "hexpm", optional: false]}, {:decimal, "~> 1.0", [hex: :decimal, repo: "hexpm", optional: false]}], "hexpm"},
+  "postgrex": {:hex, :postgrex, "0.14.1", "63247d4a5ad6b9de57a0bac5d807e1c32d41e39c04b8a4156a26c63bcd8a2e49", [:mix], [{:connection, "~> 1.0", [hex: :connection, repo: "hexpm", optional: false]}, {:db_connection, "~> 2.0", [hex: :db_connection, repo: "hexpm", optional: false]}, {:decimal, "~> 1.5", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}], "hexpm"},
+  "telemetry": {:hex, :telemetry, "0.2.0", "5b40caa3efe4deb30fb12d7cd8ed4f556f6d6bd15c374c2366772161311ce377", [:mix], [], "hexpm"},
 }
diff --git a/test/dataloader/ecto_test.exs b/test/dataloader/ecto_test.exs
index 999a118..a8a9f8a 100644
--- a/test/dataloader/ecto_test.exs
+++ b/test/dataloader/ecto_test.exs
@@ -73,7 +73,7 @@ defmodule Dataloader.EctoTest do
 
     rows = [
       %{user_id: user.id, title: "foo"},
-      %{user_id: user.id, title: "bar", deleted_at: DateTime.utc_now()}
+      %{user_id: user.id, title: "bar", deleted_at: DateTime.truncate(DateTime.utc_now(), :second)}
     ]
 
     {_, [%{id: post_id} | _]} = Repo.insert_all(Post, rows, returning: [:id])
diff --git a/test/support/test_repo.ex b/test/support/test_repo.ex
index db4f532..9246d1c 100644
--- a/test/support/test_repo.ex
+++ b/test/support/test_repo.ex
@@ -1,3 +1,5 @@
 defmodule Dataloader.TestRepo do
-  use Ecto.Repo, otp_app: :dataloader
+  use Ecto.Repo,
+    otp_app: :dataloader,
+    adapter: Ecto.Adapters.Postgres
 end